What would happen in the Senate if Supreme Court Justices Ruth Bader Ginsburg and Stephen Breyer retiredthis spring? James Taranto predicts filibusters of any would-be replacements. He also questions whether Democrats would have the votes to add high court nominations to the list of executive branch appointments that no longer require a supermajority to proceed under the rule change imposed by Democrats last year. On the other hand, Steve Klepper arguesthat the confirmations of Sri Srinivasan and Patricia Millett to the U.S. Court of Appeals for the District of Columbia last year suggests that Obama could get nominations through, even if Republicans win a Senate majority.

I'm with Taranto. There are plenty of examples of judges who were easily confirmed and then faced opposition when they were picked for the Supreme Court. I can't predict whether Srinivasan, Millett or similar candidates would be confirmed, but I'm certain their nominations would be contested.

Would Majority Leader Harry Reid and the Democrats expand the so-called nuclear option if Republicans tried to block Supreme Court nominees? The record is clear. Individual filibusters won't spark majority-imposed reform. Blockades will. If 41 or more Republicans said they would refuse to confirm any justice appointed by President Barack Obama, a change in the rules would be likely. The much harder question is what would happen if Republicans said they were eager to approve a nominee, just not the particular one before them.

It also isn't clear how far a Republican-majority Senate would be willing to go to shut down all executive and judicial branch nominations. There's no precedent for that over a full two-year Congress. But then again, there's no precedent for the filibuster-everything strategy on nominations instituted by Republicans in 2009. It's almost certain that some Republicans both in and out of the Senate would support a shut-it-down policy. There's no guarantee the bomb-throwers would win, however.

Klepper correctly points out that Supreme Court battles might squeeze out some lower court confirmations. That isn't a reason for Ginsburg and Breyer to postpone retirement, and there would be plenty of Senate floor time to get through the backlog even if two Supreme Court nominations need to be considered. I have no idea what Ginsburg and Breyer are thinking, but if their goal is to advance the principles they've fought for, resignation is the clear option.

This column does not necessarily reflect the opinion of Bloomberg View's editorial board or Bloomberg LP, its owners and investors.

(Jonathan Bernstein covers U.S. politics for Bloomberg View. He is co-editor of "The Making of the Presidential Candidates 2012." Follow him onTwitter at @JBPlainblog.)